In Volume 4, "Mystery at Adventure Lake," travel to beautiful Adventure Lake, a swimming area for all island animals. Do you think you can solve the mystery of what happened to Miss Sophie's children, Matthew and Maria? Meet Little Pearl's newest friends: Olé T the donkey, Olé T's riding companion Darwin, the lovely mermaid Sirenia, and a wise and dramatic coral reef named Charlie. Enjoy the fun as Syd and Sirenia teach Gracie the cat how to swim! Follow Little Pearl and her friends along the Old Winding River and across the Pacific Island of Luta toward the Big Purple Mountain.